This invention relates to an induction system for an engine with exhaust gas recirculation and more particularly to an engine induction and E.G.R. system that is low in cost, simple in construction and which ensures equal distribution of the exhaust gases with all cylinders of the engine.
It is well known to provide a system for recirculating a portion of the exhaust gases back into the combustion chambers so as to reduce or control the amount of nitrous oxide in the exhaust gases. Most engines are very sensitive to the amount of exhaust gases which are recirculated, and for this and other reasons, it is very important that the exhaust gases be recirculated equally to all combustion chambers of the engine. Although this can easily be done by providing separate conduits to each of the intake systems or each combustion chamber, such systems become extremely complicated, particularly when considering that the flow of exhaust gases is controlled by an exhaust gas recirculation control valve.
It is, therefore, a principal object of this invention to provide an improved induction system including E.G.R. which will ensure that the exhaust gases are equally recirculated to all of the combustion chambers of the engine through a simple and low cost structure.
Recently there has been proposed a type of induction system that is found to produce extremely good performance throughout the entire engine load and speed ranges. Such an induction system is shown in copending application Ser. No. 634,795, entitled "Intake Means Of Internal Combustion Engine" filed July 26, 1984, in the name of Masatoshi Ohmi et al, and assigned to the assignee of this invention. The induction system shown in that patent application employs a pair of plenum chambers that are spaced different distances from a given combustion chamber of the engine. Each plenum chamber serves each combustion chamber through a respective runner, and the runners associated with the closer plenum chamber are shorter and tuned for better performance at high speed. The runners going through the more distant plenum chamber are longer and are tuned for good low speed performance. Although such an induction system is extremely effective, it is difficult to ensure a simple and yet effective system for providing effective exhaust gas recirculation to all combustion chambers of such an engine.
It is, therefore, a still further object of this invention to provide an improved and simplified system for introducing exhaust gases to an engine embodying plural plenum chambers.